Pneumatic read head for document cards

ABSTRACT

A pneumatic read head or switch assembly having a row of air reception ports therein into which jetted air may flow after passing through the apertures of a document card, the reception ports being connected with air pressure responsive switches by means of equal length air passages. The switches comprise pistons movable under the influence of air pressure, and the pistons are disposed in a plurality of rows each of which extends parallel with the row of reception ports and spaced sideways therefrom. Each of the pistons is effective on the center of a bar portion of copper cladding for moving the center of the bar portion into contact with another contact, and the bar portion and other contact for each switch is surrounded by bar portions arranged in hexagonal form for providing a column of support around the switch. A rigid backing plate acted on by springs holds the parts of the switch assembly together.

United States Patent [191 Berkman et a1.

[ 51March 20, 1973 [54] PNEUMATIC READ HEAD FOR DOCUMENT CARDS [73]Assignee: lntemational Business Machines Corporation, Armonk, NY.

22 Filed: Oct. 7, 1971 21 Appl.No.: 187,491

[52] U.S. Cl. ..200/46, 200/83 N, 235/6l.ll C, 340/240 [51 Int. Cl...H0lh 43/08 [-58] Field of Search.....200/83 R, 83 N, 46; 307/118;235/6l.1l C, 61.11 R; 340/240 3,193,631 7/1965 Weingarden ..200/463,304,386 2/1967 Schlesinger, Jr..... ....200/46 X 3,614,395 10/1971Harshman .200/46 3,548,162 12/1970 Young et a]. ..235/6l.ll 3,350,51810/1967 Krakinowski et a]. ..200/83 R 3,571,542 3/1971 Madden ..200/83 NPrimary Examiner-Herman J Hohauser Attorney-Keith T. Bleuer et a1.

[ ABSTRACT A pneumatic read head or switch assembly having a row of airreception ports therein into which jetted air may flow after passingthrough the apertures of a document card, the reception ports beingconnected with air pressure responsive switches by means of equal lengthair passages. The switches comprise pistons movable under the influenceof air pressure, and the pistons are disposed in a plurality of rowseach of which extends parallel with the row of reception ports andspaced sideways therefrom. Each of the pistons is effective on thecenter of a bar portion of copper cladding for moving the center of thebar portion into contact with another contact, and the bar portion andother contact for each switch is surrounded by bar portions arranged inhexagonal form for providing a column of support around the switch. Arigid backing plate acted on by springs holds the parts of the switchassembly together.

13 Claims, 18 Drawing Figures PATENTFBmmms 372L781 SHEET 1 [1f 7 FIG@W/// H H II I! u H n u n u H I I! I H n H M I [IV/V/H.

JOHN W. BERKMAN RICHARD E LAGERGREN MERLIN J.RICKLEFS 9y WALTER S.SCHAFFER PATENTEUmzomn SHEET 2 or 7 IIIIF WOOOOO 00000000000000 FIG. 2

Pmiminmzom SHEET 8 OF 7 5 65w ooooc 0 O Q Q'Q MU PNEUMATIC READ HEAD FORDOCUMENT CARDS BACKGROUND OF THE INVENTION The invention relates topneumatic read heads or switch assemblies particularly useful forreading the apertures in document cards through which jets of air aredirected.

DESCRIPTION OF THE PRIOR ART ports in the-read head are connected bymeans of t passages with the diaphragm portions.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an improved pneumatic read head or switch assembly for apertureddocument cards having equal length air passages between air receptionports in the read head receiving air jetted through apertures in thedocument cards and air pressure responsive switches. It is contemplatedthat the air reception ports shall extend in a row disposed at rightangles to the direction of movement of the document cards and that theswitches shall be disposed in spaced rows located parallel with the rowof said ports and equidistant from the path of movement of the documentcards.

It is another object of the invention to provide an improved switchassembly in a pneumatic read head of this type which includes claddingof electrically conducting material disposed on a film diaphragm, withportions of the film being connected with the air reception ports in theread head so that the cladding is moved into electrical contact withother contacts depending on which of the ports are supplied with airunder pressure, with land patterns surrounding the cladding portionsthat move to make electrical contact for providing a column of supportaround the individual switches.

It is a further object of the invention to provide an improvedconstruction of a pneumatic read head which includes a plurality offilms and plates stacked to form the completed read head, with the stackterminating with a rigid backing plate which is held by spring pressureso as to .hold the layers of the pneumatic read head in substantiallyuniform pressure relationship with respect to each other.

In a preferred form, the pneumatic read head of the present inventionincludes a sense head having a row of air reception ports formed thereinand below which an apertured document'card may be passed for providingair under pressure into the ports'depending on which apertures exist ina column in a'document card and having equal length air passages in theform of grooves in the upper surface of the sense head which terminatein four rows extending parallel with the row of air reception ports, andthe following parts disposed successively and as layers on top of thesense head: a sense head cover having a perforation therethroughcorresponding to the termination of each of the grooves in the uppersurface of the sense head, a film diaphragm, a cavity board havingcylindrical cavities therethrough in which pistons are movably disposed,a film diaphragm having cladding on its upper surface in the form ofbars extending just above each of the rows of openings in the sense headcover and also in the form of bar portions forming hexagons that havetheir centers in alignment with the centers of the openings through thesense head cover, a thin separator having an opening therethroughcoaxially disposed with respect to the centers of the hexagonal barportions on the diaphragm just below, a contact board having a roundcladding portion disposed in alignment with each of the openings throughthe separator just below and having cladding portions in the form ofbars forming a hexagonal pattern surrounding each of the round claddingportions so as to provide a column of support along with the barportions forming the hexagonal figures in the diaphragm, and a backingplate of relatively thick, rigid material forming the upper member ofthe pneumatic read head. The backing plate is held by means of a pair ofsprings on opposite ends thereof so as to hold the layers together withsubstantially uniform pressure on each of the layers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view of the read heador switch assembly of the invention positioned over an air plenum;

FIG. 2 is a top plan view of the air plenum together with aplan view ofa document card being-moved over the air plenum;

FIG. 3 is a sectional view taken on line 33 of FIG.

FIG. 4 is an exploded view of the read head of the invention showing itscomponent parts including a sense head, a sense head cover, a firstdiaphragm, a cavity board, a second diaphragm, a separator, a contactboard, and a backing plate;

FIG. 5 is a top plan view of the sense head;

FIG. 6 is a top plan view of the sense head cover;

FIG. 7 is a top plan view of the first diaphragm;

FIG. 8 is a top plan view of the cavity board;

FIG. 9 is a sectional view on an enlarged scale taken on line 99 of FIG.2 showing a piston disposed in one of the cavities of the cavity board;

FIG. 10 is a top plan view of the second diaphragm;

FIG. 11 is a top plan view of the separator;

FIG. 12 .is a bottom view of the contact board;

FIG. 13 is a top plan view of the backing plate;

FIG. 14 is a sectional view taken on line 14-14 of FIG. 13;

FIGS. 15 and 16 are top plan views of modified forms of seconddiaphragms;

FIG. 17 is a sectional view of modified pressure applying mechanism foruse in place of the pistons received by the cavity board; and

FIG. 18 is a top plan view of a part of the modified pressure applyingmechanism taken from line l8- I8 of FIG. 17. Y

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated document cardreading system comprises, in general, a plenum l and a pneumatic readhead or switch assembly 12 positioned above the plenum (see FIGS. 1, 2,and 3). A series of document cards 14 each having punched openings 16therethrough in a plurality of columns 18, which extend transversely tothe direction A in which the cards move, may be passed between theplenum 10 and read head 12; and the read head 12 provides electricaloutput signals which correspond to the particular ones of the openings16 that exist in the columns 18.

The plenum 10 comprises a casing 20 which has an air supply opening 22in a lower portion thereof to which any suitable source of air underpressure may be connected. The plenum 20 hasan upper surface 24 which issubstantially flat and has a plurality of ports 26 extending into theinner chamber of the plenum 20. The ports 26 are arranged in a row whichis at right angles to the direction A of movement of the cards 14; andthe spacing of the ports 26 is the same as that of the holes 16 in thecard 14, assuming that in any particular column 18, all of the holes 16exist that may exist. The read head 12 is spaced from the plenum 10 bymeans of spacers 28 and 30.

The read head 12 comprises, in generaLa sense head 32, a sense headcover 34, a diaphragm 36, a cavity board 38, a diaphragm 40, a separator42, a contact board 44, and a backing plate 46 (see FIG. 4).

The sense head 32 (see FIG. 5) constitutes a plate of phenolic materialhaving a row of ports 48a 48x disposed therein. The ports 48a 48x arespaced the same distances as are the openings 26 in the plenum 10, witheach of the ports 48a 48x being directly disposed above one of theopenings 26. There may be also other ports in the sense head 32 forpurposes other than for sensing the apertures 16 in a document card 14;however, these are not important from the standpoint of the presentinvention.

The sense head cover 34 (see FIG. 6) is provided with openings 50a 50xtherethrough which correspond respectively with the openings 48a 48x, aconnection being made between the respective openings 50a 50x and theopenings 48a 48:: as will be hereinafter described. The openings 50a 50xare disposed in four rows 52a, 52b, 52c, and 52d which extend at rightangles to the direction A of movement of the document cards 14. Inparticular, the openings 50b, 50f, 50j, 50n, 50r, and 50v are disposedon the row 52a; the openings 50d, 50h, 501, 50p, 50t, and 50x aredisposed on the row 52b; the openings 50a, 50c, 50i, 50m, 50q, and 50uare disposed on'the row 52c; and the openings 50c, 50g, 50k, 500, 50s,and 50w are disposed on the row 52d.

The sense head 32 in its upper surface is provided with a plurality ofgrooves 54a 54x cut therein. The grooves 54a 54x respectively connectthe ports 48a 48x with the openings 50a 50x. The grooves 54a 54x thusrespectively have their entrance ends at the ports 48a 48x and havetheir other or exit ends in coincidence with the ports 50a 50):.Accordingly, the grooves 54b, 54f, 54j, 54n, 54r, and 54v have theirexit ends on the row 52a; the grooves 54d, 54h, 54l, 54p, 54t, and 54xhave their exit ends on the row 52b; the

grooves 54a, 54c, 54i, 54m, 54q, and 5414 have their exit ends on therow 52c; and the grooves 54c, 54g, 54k, 540, 54s, and 54w have theirexit ends on the row 52d. Each of the grooves 54a, 54e, 54i, 54m, 54q,and 54u have the same configuration and are made up of a part aextending in the direction A, a part b extending at a slight acute anglewith respect to the part a, a part 0 extending parallel with the part a,and a curved part d connecting the parts a and c. The grooves 54c, 54g,54k, 540, 54s, and 54w are identical and each comprises a part bconnected with a part e that extends parallel with the direction A and apart f connected with the part e by means of a curved part d. Thegrooves 54b, 54f, 54j, 54n, 54r, and 54v are identical with the grooves54c, 54g, 54k, 540, 54s, and 54w, but extend in the opposite direction.The grooves 54d, 54h, 54l, 54p, 54t, and 54x are identical with thegrooves 54a, 54a, 54i, 54m, 54q, and 54a, but extend in the oppositedirection. All of the grooves 54a 541: are the same in length since eachof these grooves contain the parts b and d and since the sum of thelengths of the parts a and 0 equals the sum of the lengths e andf. Thegroove portions a and c are of substantially the same length, while thegroove portions 2 are substantially longer than the groove portionsf. Itwill be noted that the groove portions e on opposite sides of acenterline C on which the ports 48a 48x are disposed are in alignment inthe-direction A; that the groove parts a are in similar alignment onopposite sides of the centerline C and that the parts c and f aresimilarly in alignment on opposite sides of the centerline C. It willalso be noted that the ports 50a 50x are of relatively smallcross-sectional size compared to the cross-sectional size of grooves 54a541: and that the ports 50a 50x each has a countersunk outlet portion 55(see FIG. 9). The ports 50a 50x thus act as air restrictions but thecountersunk portions 55 assure a relatively large area of air pressureapplication.

The diaphragm 36 (see FIG. 7) is simply a thin, flexible film which fitsover the sense head cover 34. The cavity board 38 (see FIG. 8) is arelatively rigid board of phenolic material, for example, which hasround cavities 56a 56x therethrough respectively corresponding to and inalignment with the openings 50a 50x in the sense head cover 34. Thecavity board 38 is also provided with a pair of elongate openings 58 and60. A button or piston 62 having a boss 62a on its upper surface isslidably disposed in each of the cavities 56a 56x (see FIG. 9).

The diaphragm 40 (see FIG. 10) is of relatively thin, flexible sheetmaterial and is provided with copper cladding in the form of straightsegments which provide hexagons 64a 64x that respectively have theircenters in alignment with the openings 56a 56x in the cavity board 38.The cladding is also in the form of elongate straight lines or bars 66a,66b, 66c, and 66d which are respectively in alignment with thecenterlines 52a, 52b, 52c, and 52d.

The separator 42 (see FIG. 11) is of thin material and is provided withopenings 68a 68x therethrough which are respectively in alignment withthe centers of the hexagons 64a 64x.

The contact board 44 is of relatively rigid electrical insulatingmaterial and is provided on its lower surface with copper cladding inthe form of round dots 70a 701: which have their centers in alignmentwith the centers of the openings 68a 68x respectively (see FIG. 12).Each of these dots 70a 70x is connected to a contact pin 72 for thepurpose of completing an electric circuit. It will be noted that thecladding on the contact board 44 and particularly the lines ofconnection of the circular cladding portions 70a 70): to the pins 72 isof such configuration as to form hexagonal cladding portions 74a 74x,and these hexagonal cladding portions are disposed in substantialalignment with the cladding portions forming the hexagons 64a 64x,respectively.

The backing plate 46 see FIGS. 12' and 13 is of relatively thickmaterial and may be phenolic, for example. The backing plate is providedwith elongated slots 76 and 78 therethrough, and the pins 72 projectupwardly into the slots. The backing plate 46 is held fixed with respectto the sense head 32 by means of screws 80, with the remaining parts 3444 being held captured between the plate 46 and the head 32; the springs82 are provided around the screws 80 so that the springs are heldtogether under spring pressure. The matching hexagonal cladding patternson the diaphragm 40 and contact board 44 form in effect columns ofsupport around the corresponding switches, particularly the parts of thecladding at the centers of the hexagons 64a 64x, so as to prevent thecopper cladding on the diaphragm 40 from being held in the openings 68a68:: in the separator 42 by the pistons 62 because of too much clampingpressure from the backing plate 46.

The elongate straight line 664 of cladding on the diaphragm 40 isprovided with a contact point 84 which is held in contact by anysuitable means with a contact point 86 formed of the copper cladding onthe contact board 44 and connected with one of the contact pins 72. Thisconnection allows an electric circuit to be completed from the pin 72connected with the point 86 and any of the other pins 72 in accordancewith the particular piston 62 that has air pressure applied to it bymeans of the diaphragm 36.

In operation, air under a low pressure, such as l pound/square inch, isdischarged into the plenum l0 and .tends to jet through the ports 26. ifa document card 14 located between the plenum l0 and the read head 12 atthe'tim'e has an aperture 16 located between a port 26 and one of theports 48a 48x, air under pressure travels through the correspondinggroove 54a 54x, through the corresponding opening 50a 50x and intocontact with the portion of the diaphragm 36 located just above theopening 50a 501. The corresponding piston 62 located in thecorresponding opening 56a 56): moves upwardly and moves its boss portion62a into contact with the diaphragm 40 and flexes the portion of thecladding bar portions 66a 660 located in the corresponding hexagon 64a64x so as to move this bar portion through the corresponding opening 68a68x in the separator 42 into contact with the corresponding circularcontact portion 70a 70x thus completing an electric circuit through thecircular contact portion to the corresponding pin 72. The ports 48a 48::are small in diameter at their lower ends relative to the upper parts ofthe ports and to the connected grooves 54a 54):, as may be seen fromFIG. 9, and thus function to prevent undue turbulence in thecorrespondmg grooves 54a 54x and in the upper relatively large diameterparts of the ports 48a 48x so as to prevent bounce of the pistons 62with corresponding unreliable switch contact and reading of apertures16.

Although the portions of the cladding defining the hexagon portions 64a64x is preferred for spacing purposes, these hexagon defining claddinglines may be dispensed with if desired, relying on only elongate lineportions corresponding to the portions 66a 66d for the purpose ofcompleting the electric circuits. A diaphragm 40A or this type isillustrated in FIG. 15 and includes the connected elongate lines ofcladding 66aa, 66kb, 66cc, and 66dd.

The diaphragm 40 may be replaced if desired by a diaphragm 403 (see FIG.16) having copper cladding thereon which is in the form of connectedcircles 84a 84x. The peripheries of the circles 84a 84x respectivelytake the place of the hexagons 64a 64.x, and the circles 84a 84::function in substantially the same manner as the hexagons 64a 64x. Theperipheries of the circles and the hexagons function as uniform spacers;and the central portions of the circles and the cladding lines 66a 66dfunction in a similar manner completing the respective electriccircuits.

If desired, the cavity'board 38 and the pistons 62 may be replaced by athin metal sheet 88 and a separator 90. The sheet 88 is provided with aplurality of hinged plates 92a -.92x which are respectively disposedover the openings 50a 50x. An arcuate slot 94 separates each of theplates 92a 92x from the rest of the sheet 88, and a hinge portion 96connects the plate to the rest of the sheet 88. Each of the plates 92a92.1: is provided with a central raised dimple 98. The separator isprovided with openings a 100x therethrough in alignment with thecorresponding hinged plates 92a 92x and hexagons 64a 64x. Thisembodiment of the invention functions in substantially the same manneras described in connection with the first-mentioned embodiment, with thehinged plates 92a 92x being acted on by the diaphragm 36 andparticularly the portions of the diaphragm 36 located beneath the hingedplate portions 92a 921:, for the purpose of moving the dimple 98 on thehinged plate into contact with the diaphragm 40 for the purpose ofmaking the corresponding electrical contacts.

The above-described pneumatic read head advantageously allows the use ofa very low operating pressure, such as l pound/square inch, of airsupplied to the plenum 10 while yet providing a reliable reading of theapertures 16 in document card 14. It is only necessary for the pistons62 or the parts 92a 92x to move through a slight distance so as toengage the cladding on the diaphragm 40, 40A or 403 with contact board44 in order to complete the electrical circuits corresponding with theparticular ports 48a 48x to'which jets of air are supplied from theports 26 through apertures 16 in a document card 14. The

grooves 54a 54x are all of the same length since each ofthem includes arounded portion d and an acutely extending portion 12 in addition toparts a and c or parts e andfextending in the direction A which addtogether to the same length. The response to air jetting through theapertures 16 in a card 14 is thus the same insofar as the time ofapplication of air pressure to a piston 62, for example, with respect tothe time of application of air to the corresponding ports 48a 482:.Thus, reliable reading of the apertures 16 in document cards 14 isobtained even though the cards 14 are passed across the ports 48a 48x atvery high speeds.

The hexagon shaped cladding 64a 64x on the diaphragm 40 advantageouslyprovides a proper spacing between the diaphragm 40, the separator 42 andthe round contact cladding parts 70a 70x on the contact board 44,although, as above mentioned, the hexagon shaped cladding portions 64064x may be dispensed with, if desired. The upper countersunk portions 55ofthe ports 50a 50x advantageously provide a relatively large area ofair application on the diaphragm 36, even through the ports 50a 50:: inthemselves act as relatively small diameter air restrictions. The ports26 and ports 48a 48x likewise are relatively small in diameter and actas air restrictions to increase the reliability of reading by the readhead. The backing plate 46 is relatively thick and stiff; and, acting inconjunction with the springs 82, the plate 46 holds the parts of theread head together with a uniform pressure over substantially all of theparts between the sense head 32 and the plate 46.

The pneumatic read head 12, although providing the reliability of anelastic diaphragm switch, nevertheless is a relatively low costconstruction.

We claim:

1. A pneumatic switch assembly for reading document cards having columnsof apertures therein, comprising:

a sense head member having a plurality of air reception ports on a facethereof across which the documentcards may be passed so that air may bejetted through the card apertures into said ports,

an air pressure responsive piston corresponding to each of said ports,

means forming a cavity in which each of said pistons is disposed andeach cavity having an air entrance opening, some of said ports beinglocated at different distances with respect to their correspondingcavity openings than others of said ports,

electric switch means actuated by each of said pistons when air underpressure is supplied to the piston, and

means providing air passages which connect said cavity openings with therespective ones of said air reception ports, at least some of saidpassages having bends in them to be longer than the shortest distancebetween said corresponding ports and openings and so that all of saidpassages are of the same length.

2. A pneumatic switch assembly as set forth in claim 1, said airpassages for most of their lengths constituting grooves formed in a faceof said sense head member opposite to said face having said airreception ports therein.

3. A pneumatic switch assembly as set forth in claim 2, each of saidgrooves having a portion extending in the same direction as thedirection of movement of said document cards and also having a portionextending in the opposite direction.

4. A pneumatic switch assembly as set forth in claim 3, said airreception ports and said cavities having their axes extending in thesame direction and said ports being disposed in a row, some of saidcavities being disposed in a pair of rows that are parallel with saidrow of air reception ports with one of the rows of cavities beinglocated more remotely from the row of air reception ports than the othersaid row of cavities.

5. A pneumatic switch assembly as set forth in claim 4, each of saidgrooves including a groove portion in the form of a half circleconnecting said two groove portions extending in the direction of cardmovement and opposite thereto and also including a slantwise extendinggroove portion extending at an acute angle with respect to the directionof card movement.

6. A pneumatic switch assembly as set forth in claim 5, said slantwiseextending groove portion being connected directly with the correspondingair reception port and with a first one of said two groove portionsextending in the direction of card movement and opposite thereto, saidgroove in the form of a half circle connecting the second one of saidtwo groove portions extending in the direction of card movement andopposite thereto with said first such groove portion.

7. A pneumatic switch assembly as set forth in claim 6, said two rows ofcavities being disposed on one side of said row of ports, and others ofsaid cavities being disposed on the other side of said row of ports andbeing connected with the corresponding ones of said air reception portswith grooves of the same length and of the same type located in saidsense head member as said grooves connecting said two first named rowsof cavities with the corresponding ones of said air reception ports.

8. A pneumatic switch assembly as set forth in claim 7, said firstgroove portion extending in the same or opposite directions with respectto card movement for each said cavity of said outermost pair of rows ofsaid cavities being longer than said second groove portion for the samegroove and extending in the same or in the opposite direction withrespect to card movement.

9. A pneumatic switch assembly as set forth in claim 8, said first andsecond groove portions extending in the same or opposite directions withrespect to card movement for each cavities of said innermost pair ofrows being of substantially the same length.

10. A pneumatic switch assembly for reading document cards havingcolumns of apertures therein comprising: means providing on a face ofthe switch assembly a row of air reception ports across which thedocument cards may be passed so that air may be jetted through the cardapertures into said row of ports,

an air pressure responsive piston means connected to each of said ports,and

electric switch means actuated by said piston means when air underpressure is supplied thereto and including a flat-faced film diaphragmhaving contact portions carried on the flat face thereof correspondingto each of said piston means, said switch means also including aflat-faced contact board having a contact portion disposed on the flatface thereof opposite to each of said first named contact portions,

either said film diaphragm or said contact board on the flat facethereof being provided with a land pattern of cladding ringing thecontact portion carried thereon for forming a column of support aroundthe contact portion.

11. A pneumatic switch assembly as set forth in claim 10, the other ofsaid contact board or film diaphragm also being provided with a landpattern ringing the contact portion thereon for cooperating with saidfirstnamed land pattern so as to provide a column of support around saidcontact portions.

12. A pneumatic switch assembly for reading document cards havingcolumns of apertures therein, comprising:

a sense head having a row of air reception ports on a face thereofacross which the document cards may be passed so that air may be jettedthrough the card apertures into said row of ports,

a film diaphragm overlying said sense head,

means for providing an air passage connecting each of said air receptionports with a portion of said diaphragm so that the diaphragm acts as apiston portion for each of said ports,

a sheet containing a plurality of movable piston parts therein eachcoaxially disposed with respect to the piston portions in saiddiaphragm,

switch means for each of said piston parts and including a filmdiaphragm carrying electric contact portions and also including acontact board having a contact portion for each of said first-named con-2 tact portions for completing an electrical circuit when said contactportions are moved into contact with flexing of the diaphragm,

a separator sheet disposed between said secondnamed film diaphragm andsaid contact board and having an opening therethrough corresponding toeach of said first-named contact portions,

a rigid backing plate overlying said sense head, said sheet containingsaid movable piston parts, said film diaphragms, said separator sheet,and said contact board, and

spring means effective on said backing plate so as to maintainsubstantially the same pressure over said sense head, said filmdiaphragm, said sheets, and said contact board.

13; A pneumatic switch assembly as set forth in claim 12, and alsoincluding a sense head cover disposed between said sense head and saidfirst-named film diaphragm and having an opening therethroughcorresponding to each of said piston portions, said sheet containingsaid movable piston parts constituting a cavity board having a pluralityof cavities therethrough and said piston parts each constituting aseparate piston disposed in one of said cavities.

(5?) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent3.721.781

Dated -g on 1 Q7;

Inventofls) J. W. Berkman, R. E. Laqerqren. M. J, Ricklefs and W. S.Schaffer It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected 'as shownbelow:

In the specification:

Column 5, line 20, "the" (third occurrence) should be -and-.

line 22, "springs" should be --parts--.

line 57, "660" should be -66d.

In the claims:

Column 8, line 42, "cavities" should be --said caVity-.

Column 9, line 3, after "pattern", insert of cladding-r.

si ned and sealed this 2nd day of April 197i.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer c. MARSHALL DANN- Commissionerof Patents eme Q W105) I UNITED STATES PATENT OFFICE fi (5 7 CERTIFICATEOF CORRECTION Patent No 3,7 1,731 Dated March on 1 on Invencor(s) J. W.Berkman, R. E. Laqerqren. M. J. Bicklefs and W. S. ,Schaffer It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected -as shown below:

In the specification: I

Column 5, line '20, "the" (third occurrence) should be --and.

line 22, "springs" should be --parts-.

line 57, "66c" should be 66d-.

In the claims I I Column-8, line 42, "cavities" should be said caVity.

Column 9', line 3, after "pattern", insert of cladding-r.

Signed and sealed this 2nd day of April 1971 (SEAL) I Y Y Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN- Attesting Officer Commissionerof Patents

1. A pneumatic switch assembly for reading document cards having columnsof apertures therein, comprising: a sense head member having a pluralityof air reception ports on a face thereof across which the document cardsmay be passed so that air may be jetted through the card apertures intosaid ports, an air pressure responsive piston corresponding to each ofsaid ports, means forming a cavity in which each of said pistons isdisposed and each cavity having an air entrance opening, some of saidports being located at different distances with respect to theircorresponding cavity openings than others of said ports, electric switchmeans actuated by each of said pistons when air under pressure issupplied to the piston, and means providing air passages which connectsaid cavity openings with the respective ones of said air receptionports, at least some of said passages having bends in them to be longerthan the shortest distance between said corresponding ports and openingsand so that all of said passages are of the same length.
 2. A pneumaticswitch assembly as set forth in claim 1, said air passages for most oftheir lengths constituting grooves formed in a face of said sense headmember opposite to said face having said air reception ports therein. 3.A pneumatic switch assembly as set forth in claim 2, each of saidgrooves having a portion extending in the same direction as thedirection of movement of said document cards and also having a portionextending in the opposite direction.
 4. A pneumatic switch assembly asset forth in claim 3, said air reception ports and said cavities havingtheir axes extending in the same direction and said ports being disposedin a row, some of said cavities being disposed in a pair of rows thatare parallel with said row of air reception ports with one of the rowsof cavities being located more remotely from the row of air receptionports than the other said row of cavities.
 5. A pneumatic switchassembly as set forth in claim 4, each of said grooves including agroove portion in the form of a half circle connecting said two grooveportions extending in the direction of card movement and oppositethereto and also including a slantwise extending groove portionextending at an acute angle with respect to the direction of cardmovement.
 6. A pneumatic switch assembly as set forth in claim 5, saidslantwise extending groove portion being connected directly with thecorresponding air reception port and with a first one of said two grooveportions extending in the direction of card movement and oppositethereto, said groove in the form of a half circle connecting the secondone of said two groove portions extending in the direction of cardmovement and opposite thereto with said first such groove portion.
 7. Apneumatic switch assembly as set forth in claim 6, said two rows ofcavities being disposed on one side of said row of ports, and others ofsaid cavities being disposed on the other side of said row of ports andbeing connected with the corresponding ones of said air reception portswith grooves of the same length and of the same type located in saidsense head member as said grooves connecting said two first named rowSof cavities with the corresponding ones of said air reception ports. 8.A pneumatic switch assembly as set forth in claim 7, said first grooveportion extending in the same or opposite directions with respect tocard movement for each said cavity of said outermost pair of rows ofsaid cavities being longer than said second groove portion for the samegroove and extending in the same or in the opposite direction withrespect to card movement.
 9. A pneumatic switch assembly as set forth inclaim 8, said first and second groove portions extending in the same oropposite directions with respect to card movement for each cavities ofsaid innermost pair of rows being of substantially the same length. 10.A pneumatic switch assembly for reading document cards having columns ofapertures therein comprising: means providing on a face of the switchassembly a row of air reception ports across which the document cardsmay be passed so that air may be jetted through the card apertures intosaid row of ports, an air pressure responsive piston means connected toeach of said ports, and electric switch means actuated by said pistonmeans when air under pressure is supplied thereto and including aflat-faced film diaphragm having contact portions carried on the flatface thereof corresponding to each of said piston means, said switchmeans also including a flat-faced contact board having a contact portiondisposed on the flat face thereof opposite to each of said first namedcontact portions, either said film diaphragm or said contact board onthe flat face thereof being provided with a land pattern of claddingringing the contact portion carried thereon for forming a column ofsupport around the contact portion.
 11. A pneumatic switch assembly asset forth in claim 10, the other of said contact board or film diaphragmalso being provided with a land pattern ringing the contact portionthereon for cooperating with said first-named land pattern so as toprovide a column of support around said contact portions.
 12. Apneumatic switch assembly for reading document cards having columns ofapertures therein, comprising: a sense head having a row of airreception ports on a face thereof across which the document cards may bepassed so that air may be jetted through the card apertures into saidrow of ports, a film diaphragm overlying said sense head, means forproviding an air passage connecting each of said air reception portswith a portion of said diaphragm so that the diaphragm acts as a pistonportion for each of said ports, a sheet containing a plurality ofmovable piston parts therein each coaxially disposed with respect to thepiston portions in said diaphragm, switch means for each of said pistonparts and including a film diaphragm carrying electric contact portionsand also including a contact board having a contact portion for each ofsaid first-named contact portions for completing an electrical circuitwhen said contact portions are moved into contact with flexing of thediaphragm, a separator sheet disposed between said second-named filmdiaphragm and said contact board and having an opening therethroughcorresponding to each of said first-named contact portions, a rigidbacking plate overlying said sense head, said sheet containing saidmovable piston parts, said film diaphragms, said separator sheet, andsaid contact board, and spring means effective on said backing plate soas to maintain substantially the same pressure over said sense head,said film diaphragm, said sheets, and said contact board.
 13. Apneumatic switch assembly as set forth in claim 12, and also including asense head cover disposed between said sense head and said first-namedfilm diaphragm and having an opening therethrough corresponding to eachof said piston portions, said sheet containing said movable piston partsconstituting a cavity board having a plurality of cavities therethroughand said piston parts each constituTing a separate piston disposed inone of said cavities.